Customizing Aggregates

When you select an aggregate, the Pentaho Aggregation Designer pulls information from the schema file to display its dimensions and levels. You can modify any aggregate the Pentaho Aggregation Designer recommends, customizing it for your needs. You can also create an aggregate from scratch and delete aggregates you do not want.

Impact summary

The impact summary in the lower right pane provides you with information on the estimated impact for creating all of the currently selected aggregates. This summary includes the number of aggregate tables that will be created, the estimated number of rows contained in those tables, and the estimated amount of space it will occupy on the hard drive. The impact summary is automatically updated as you select and deselect aggregates from the list of proposed aggregates.

Cost/benefit chart

The Cost/Benefit chart provides a high-level comparison of the benefit of all currently selected aggregates relative to their estimated cost. The benefit scale represents the relative number of queries that can be fulfilled by an aggregate table versus having to be retrieved from the base fact table. The cost scale is an indicator of the impact in terms of number of tables and disk space needed to create the selected aggregate recommendations.

Saving your design

The Pentaho Aggregation Designer allows you to save all aggregate-related data (custom- or advisor-created) in your workspace at any time. Saving ensures that all of the data (your designs) in the workspace is retained; you are saving the state of your workspace as an XML file in a location you specify. To save, go to the File menu and click Save As. To open a saved file, go to the File menu and click Open, then navigate to the design you previously saved.